Spicules

Spicules are tiny needle-like elements of silica forming the sponge skeleton.

Body spicules are termed megascleres (M) or microscleres (m), depending on their size. Spicules in the outer coat of the gemmule are called gemmoscleres (g or g1, g2 if differing).

Gemmoscleres

Shaped like an axle with a disk at each end

Shaped like a dumbbell with hooks at the tips
Of 2 kinds, both the axle-with-disks kind and the hooked kind
Lacking structures at the tips

Spicules are tiny needle-like elements of silica forming the sponge skeleton.

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